The goals of this project are to characterize phenotypes of spermatogenesis mutants and to develop resource for gene expression analysis of spermatogenesis and cell-cell interaction in the testis. With whole-genome mutagenesis and screening for infertility mutants, there is now opportunity to bring unprecedented mutant resources to the reproductive biology community. In this project a detailed analysis of the phenotypes of induced mutations that affect spermatogenesis and sperm function will be conducted by studying testis and germ-cell morphology, gene expression and function of sperm in fertilization in vitro. A more detailed analysis of mutants impaired in meiotic cell-cycle progress or characterized by elevated sperm aneuploidy will involve localization of meiotically important proteins, test of nuclear competence for the meiotic division and analysis of germ-cell autonomy of mutant gene action. These analyses are essential first steps, forming a solid foundation for follow-on investigations, and may also suggest candidate genes to guide the gene cloning efforts (Project by Schimenti). Molecular characterization of spermatogenesis mutants will require analysis of gene expression profiles of spermatogenic cells and their supporting Sertoli cells. Thus, the focus off the second goal is to build resources for expression profiling of mutants. Marker gene sequences,, characteristic of spermatogenic stages and of Sertoli cell response to spermatocyte co-culture, will be identified and used for phenotype characterization of induced male sterility mutants. By these two goals this project will contribute to the program's overall effect of discovering and defining the functional genomics of gametogenesis.